Omega Loop Versus Roux-en-Y Gastric Bypass (YOMEGA)

Prospective Multicentric Randomized Trial of Efficiency and Safety of Laparoscopic Omega Loop Bypass Versus Roux-en-Y Gastric Bypass

Several prospective trials and metaanalysis have demonstrated the superiority of bariatric surgery on the medical treatment of obesity. The Roux-en-Y Gastric ByPass (RYGBP) procedure has been practiced for more than 30 years, and is the procedure of choice for morbidly obese with metabolic disorders in most of the reference centers. Nevertheless, the RYGBP is a technically demanding procedure with a learning curve of more than 75 cases. The complication rate is around 10% in expert centers.

More recently another procedure has been described which seems as efficient on weight loss and co-morbidities as the RYGBP, with the advantage of being less technically difficult and less morbid, especially for multi-complicated obese and/or the super obese. It consists of a unique gastro-jejunal anastomosis between a long gastric pouch and a jejunal Omega loop. However, this procedure could be at risk of biliary reflux and anastomotic ulcers with dysplastic changes of the gastric and esophageal mucosa. As a result, the Omega loop bypass (OLB) has only been developed by a few teams and remains a controversial subject, particularly as only one monocentric randomized trial has compared it to the RYGBP, which is remains the gold standard. The first litterature results show similar or even better weight loss efficiency than RYGBP with a better feasibility. The early complication rate seems lower, but there are still insufficient data on long term morbidity and biliary reflux consequences.

By performing a randomized and prospective comparison of OLB to RYGBP, the aim of the investigators study is to analyze the weight loss efficiency, the morbidity and mortality, the feasibility, and the quality of life of both techniques, in order to validate the Omega loop bypass as a procedure of choice in bariatric surgery

Hypothesis :

The OLB, while being as efficient as RYGBP on weight loss and metabolic complications, could be less morbid.

Study Overview

• Status: Completed
• Conditions: Obesity
• Intervention / Treatment: Procedure: Laparoscopic Mini-gastric bypass; Procedure: Procedure of reference in bariatric surgery

• Study Type: Interventional
• Enrollment (Actual): 256
• Phase: Not Applicable

Contacts and Locations

Study Locations

• France
  • Grenoble, France, 38043
    • Clinique Universitaire de Chirurgie Digestive et de l'Urgence - CHU de Grenoble
  • Guilherand-Granges, France, 07500
    • Cabinet de chirurgie générale, digestive et de l'obésité - Hôpital Privé Drôme et Ardèche
  • Lille, France, 59037
    • Service de Chirurgie Générale et Endocrinienne - Hôpital Claude Huriez - CHU de Lille
  • Lyon, France, 69437
    • Service de Chirurgie Digestive - Hôpital Edouard Herriot - Hospices Civils de Lyon
  • Paris, France, 75013
    • Service de Chirurgie Digestive et Hépato-Bilio-Pancréatique et Transplantation Hépatique - Hôpital de la Pitié Salpêtrière
  • Paris, France, 75908
    • Service de Chirurgie Digestive, Générale et Cancérologique - Hôpital Européen Georges Pompidou - APHP
  • Saint-Etienne, France, 42100
    • Service de Chirurgie Générale - Hôpital Privé de la Loire
  • Saint-Germain-en-Laye, France, 78100
    • Service de Chirurgie Générale, Digestive et Viscérale - Centre Hospitalier Intercommunal de Poissy / Saint Gerrmain en Laye
  • Saint-Grégoire, France, 35768
    • Service de Chirurgie Digestive et Hépato-Biliaire-Centre Hospitalier Privé Saint Grégoire

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 65 years (Adult, Older Adult)
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Aged between 18 and 65 years old
• Morbid obesity with BMI ≥ 40 kg/m2 or BMI ≥ 35 kg/m2 associated with one or more co-morbidities (type 2 diabetes, arterial hypertension, sleep apnea, dyslipidemia, arthritis)
• Patient who has benefited from an upper GI endoscopy with biopsies
• Patient who has benefited from a pluridisciplinary evaluation, with a favorable opinion for a gastric bypass
• Patient who understands and accepts the need for a long term follow-up
• Patient who agrees to be included in the study and who signs the informed consent form
• Patient affiliated to a healthcare insurance plan

Exclusion Criteria:

• History of esophagitis on upper GI endoscopy (Los Angeles classification)
• Severe gastroesophageal reflux disease (GERD), resistant to medical treatment
• Presence of dysplastic modifications of the gastric mucosa or a history of gastric cancer, on upper gastrointestinal endoscopy.
• Presence of Helicobacter Pylori resistant to medical treatment
• Presence of an unhealed gastro-duodenal ulcer or an ulcer diagnosed less than 2 months previously
• History of previous bariatric surgery (gastric band, sleeve gastrectomy, vertical banded gastroplasty)
• Presence of a severe and evolutive life threatening pathology, unrelated to obesity
• Presence of chronic diarrhea (≥ 3 loose or liquid stools per day, over a period of more than 4 weeks)
• Pregnancy or desire to be pregnant during the study
• Binge eating disorders or other eating disorders according to DSM V criteria
• Mentally unbalanced patients, under supervision or guardianship
• Patient who does not understand French/is unable to give consent
• Patient not affiliated to a French or European healthcare insurance
• Patient who has already been included in a trial which has a conflict of interests with the present study

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Laparoscopic Omega Loop Bypass; Laparoscopic Mini-gastric bypass	Procedure: Laparoscopic Mini-gastric bypass; The laparoscopic Omega Loop Bypass will consist of: a long gastric tube, stapled approximately 1.5 cm from the left of the lesser curvature of the antrum to the angle of His; a narrow gastric tube will be calibrated to be approximately 1.5 cm wide; an Omega loop of 200 cm; a unique gastro-jejunal anatomosis of 200cm from the ligament of Treitz, using a linear stapler
Active Comparator: Laparoscopic Roux-en-Y Gastric ByPass; Procedure of reference in bariatric surgery	Procedure: Procedure of reference in bariatric surgery; The laparoscopic Roux-en-Y Gastric Bypass will consist of: a small gastric pouch (about 30cc); an antecolic alimentary limb; a gastro-jejunal anastomosis using a linear stapler; a 150cm long alimentary limb; a 50cm biliary limb; a latero-lateral jejuno-jejunal anastomosis; closure of the mesenteric defects

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Weight loss assessment according to Excess BMI Loss percentage (EBL%)	Weight loss assessment according to Excess BMI Loss percentage (EBL%), calculated using the following formula: ((BMI 2 years after surgery - initial BMI) / (initial BMI - 22.5)) X 100	2 years after surgery

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Weight loss according to absolute weight loss (aWL in kg), Excess Weight Loss percentage (EWL%), EBL%		1, 3, 6, 12, 18 and 24 months after surgery
Waist size reduction according to absolute waist size (in cm)		1, 3, 6, 12, 18 and 24 months after surgery
Medical and surgical complication rates	Medical and surgical complication rates (anastomotic leaks, biliary reflux, bowel obstruction, anastomotic ulcers, anastomotic stenosis, internal hernia, chronic gastritis, esophagitis, iron deficiency anemia …)	1, 12 and 24 months after surgery
Type and severity of complications	Type and severity of early and late complications for each procedure, according to the Dindo-Clavien classification	During the month following surgery (for early complications) and from one month to 24 months postoperatively (for late complications)
Operative time	Operative time (expressed in minutes)	Recorded on the day of surgery (Day 0)
Mean length of stay	Mean length of stay based on the number of days of hospitalization from surgery (Day of surgery = D0) until the end of hospitalization	Average period of 5 days from surgery (Day of surgery = D0) until the end of hospitalization, recorded on Visit 4 (Month1 +/- 10 days)
Patient's quality of life	Patient's quality of life score according to the IWQOL questionnaire and the BAROS questionnaire adapted to bariatric surgery	The day before surgery (D-1) and 6, 12 and 24 months after surgery
Metabolic and lipid profile	Metabolic profile of glucose homeostasis and the lipid profile according to antidiabetic and anitilipidemic treatments, HbA1c level, fasting glycemia, HDL, LDL and TG.	During the period of inclusion (D-60 to D-2) and at 6, 12 and 24 months after surgery
Dumping syndrome and hypoglycemia symptoms	Dumping syndrome and hypoglycemia symptoms will be assessed using the Sigstad questionnaire	At 1, 3,6,12,18 and 24 months after surgery
Gastroesophageal reflux	Gastroesophageal reflux assessed by items 5 and 27 of the GIQLI questionnaire	The day before surgery (Day-1) and 6, 12, and 24 months after surgery
Modifications of the gastric and esophageal mucosa	Histological modifications of the gastric and esophageal mucosa, based on upper GI endoscopy with biopsies	2 years after surgery
Frequency of diarrhea	Frequency of diarrhea based on items 7, 30, 31 and 36 of the GIQLI questionnaire	The day before surgery (day-1) and 6, 12, and 24 months after surgery
Nutritional status	Nutritional status, assessed by PTH, vitamin B1, B9, B12, and D levels before and 12 and 24 months after surgery and assessed by hemoglobin, albumin, prealbumin, ferritin, saturation coefficient, before and 6, 12 and 24 months after surgery .	During the period of inclusion (D-60 to D-2) and 6, 12, and 24 months after surgery (The 24-hour steatorrhea will be quantified at 6 months).

Collaborators and Investigators

• Sponsor: Hospices Civils de Lyon
• Investigators: Principal Investigator: Maud ROBERT, MD, Service de Chirurgie Digestive - Hôpital Edouard Herriot - Hospices Civils de Lyon - France

Publications and helpful links

General Publications

• Robert M, Espalieu P, Pelascini E, Caiazzo R, Sterkers A, Khamphommala L, Poghosyan T, Chevallier JM, Malherbe V, Chouillard E, Reche F, Torcivia A, Maucort-Boulch D, Bin-Dorel S, Langlois-Jacques C, Delaunay D, Pattou F, Disse E. Efficacy and safety of one anastomosis gastric bypass versus Roux-en-Y gastric bypass for obesity (YOMEGA): a multicentre, randomised, open-label, non-inferiority trial. Lancet. 2019 Mar 30;393(10178):1299-1309. doi: 10.1016/S0140-6736(19)30475-1. Epub 2019 Mar 6.
• Robert M, Poghosyan T, Maucort-Boulch D, Filippello A, Caiazzo R, Sterkers A, Khamphommala L, Reche F, Malherbe V, Torcivia A, Saber T, Delaunay D, Langlois-Jacques C, Suffisseau A, Bin S, Disse E, Pattou F. Efficacy and safety of one anastomosis gastric bypass versus Roux-en-Y gastric bypass at 5 years (YOMEGA): a prospective, open-label, non-inferiority, randomised extension study. Lancet Diabetes Endocrinol. 2024 Apr;12(4):267-276. doi: 10.1016/S2213-8587(24)00035-4. Epub 2024 Mar 4.

Study record dates

Study Major Dates

• Study Start (Actual): May 1, 2014
• Primary Completion (Actual): March 1, 2018
• Study Completion (Actual): March 1, 2018

Study Registration Dates

• First Submitted: May 12, 2014
• First Submitted That Met QC Criteria: May 13, 2014
• First Posted (Estimated): May 15, 2014

Study Record Updates

• Last Update Posted (Estimated): December 19, 2025
• Last Update Submitted That Met QC Criteria: December 13, 2025
• Last Verified: December 1, 2025

More Information

Terms related to this study

• Keywords: Bariatric surgery; Gastric bypass; Obesity -
• Additional Relevant MeSH Terms: Nutrition Disorders; Overnutrition; Body Weight; Overweight; Pathological Conditions, Signs and Symptoms; Nutritional and Metabolic Diseases; Signs and Symptoms; Obesity; Therapeutics; Surgical Procedures, Operative; Bariatrics; Obesity Management; Bariatric Surgery
• Other Study ID Numbers: 2014.851